为了适应富水中砂地层盾构掘进，需要对原有刀盘结构进行改造，并研究改造前后的刀盘力学特性。采用理论计算土压平衡和土压不平衡2种工况下的刀盘外载，并利用有限元法分析改造前后盾构刀盘的应力及变形情况。研究结果表明： 1）土压不平衡工况下的最大等效应力和最大变形高于土压平衡工况。2）对于同一种工况，改造前后刀盘的最大等效应力变化不大，但最大变形量增加了10%左右； 最大等效应力位于刀盘背板与牛腿的连接处，最大变形发生在刀盘左下侧及右上侧的边缘位置。改造后刀盘的强度和刚度均满足施工要求，实际掘进效果良好，掘进效率明显提升。

The original structure of the cutterhead needs to be improved; and the mechanical properties of the cutterhead need to be analyzed before and after modification so as to realize shield tunneling in medium sand stratum with rich water. The theoretical calculation of the cutterhead load under conditions of earth pressure balance and unbalance is implemented; and then the finite element method is used to study the stress and deformation of shield cutterhead before and after modification. The study results show that: 1）The maximum equivalent stress and the maximum deformation of the cutterhead under condition of earth pressure unbalance are higher than that under condition of earth pressure balance. 2）For the same condition, the maximum equivalent stress of cutterhead varies little before and after modification; while the maximum deformation increased by about 10%; the maximum equivalent stress is located in the cutter plate and the bracket; and the maximum deformation is located in the bottomleft edge and the aboveright edge of the cutterhead. After modification, the strength and rigidity of the cutterhead can meet the construction requirements; and it has good tunneling effect and efficiency.